Cirrus Logic CDB5376 - Manual (Page 29)

CDB5376
DS612DB3 29
Many connections to the C8051F320 microcontroller are inactive by default, but are provided for conve-
nience during custom reprogramming. Listed below are the default active connections to the microcon-
troller and how they are used.
2.3.4.1 SPI Interface
The microcontroller SPI interface communicates with the CS5376A digital filter to write/read configuration
information from the SPI 1 port and collect conversion data from the SD port. Detailed information about
interfacing to the digital filter SPI 1 and SD ports can be found in the CS5376A data sheet.
The hardware connection of the microcontroller MISO_MC pin is selected automatically within the inter-
face CPLD depending on the state of the digital filter SDRDYz pin. By default, SDRDYz is high and the
CS5376A SPI 1 port MISO pin is connected to the microcontroller MISO_MC pin, but when conversion
data becomes available from the CS5376A SD port, SDRDYz goes low and the SDDAT pin is connected
instead.
2.3.4.2 USB Interface
The microcontroller USB interface communicates with the PC evaluation software to receive configuration
commands and return collected conversion data. The USB interface uses the Silicon Laboratories API
and Windows drivers, which are available free from the internet (
http://www.silabs.com ).
2.3.4.3 Reset Source
By default, the C8051F320 microcontroller receives its reset signal from the RESET_PBz push button.
2.3.4.4 Clock Source
By default, the C8051F320 microcontroller uses an internally generated 12 MHz clock for compatibility
with USB standards.
2.3.4.5 Timebreak Signal
By default, the C8051F320 microcontroller sends the TIMEB_MC signal to the digital filter for the first col-
lected sample of a data record. Typically, some number of initial samples are skipped during data collec-
tion to ensure the CS5376A digital filters are fully settled, and the timebreak signal is automatically set for
the first “real” collected sample.
2.3.4.6 C2 Debug Interface
Through the PC evaluation software, the microcontroller default firmware can be automatically flashed to
the latest version without connecting an external programmer. To flash custom firmware, software tools
and an inexpensive hardware programmer that connects to the C2 Debug Interface on CDB5376 is avail-
able for purchase from Silicon Laboratories (DEBUGADPTR1-USB).
2.3.5 Phase Locked Loop
To make synchronous analog measurements throughout a distributed system, a synchronous system
clock is required to be provided to each measurement node. For evaluation testing purposes, a BNC clock